Reversible percussion device

ABSTRACT

Pneumatic reversible percussion device used for making holes in the ground. The device is characterized in that under the action of compressed air the striker reciprocates in a hollow housing and delivers percussions upon the latter, thereby making the device move in to the ground. The compressed air is supplied into working chambers of the housing along an air-supplying bushing having ports provided on its portion interacting with the striker, overlapped by a slide valve during the forward movement of the device and used to outstrip the supply of compressed air into a front chamber during the reverse movement of the device. The slide valve is rigidly connected with a spring-loaded sleeve that is loosely mounted on the bushing and is actuated by a spring when the device is switched over to a reverse movement by way of dropping the pressure, as compared to the nominal one.

United States Patent 1 Sudnishnikov et al.

[ 1 3,744,576 1 Jul '10, 1 973 REVERSIBLE PERCUSSION DEVICE [76]Inventors: Boris Vasilievich Sudnishnikov,

Krasny prospekt, 56, kv. 59; Alexandr Dmitrievich Kostylev, ulitsaDerzhavina, la, kv. 44; Konstantin Stepanovich Gurkov, ulitsaDerzhavina, la, kv. 68; Konstantin Konstantinovich Tupitsyn, ulitsaKrylova, 3, kv. 37; Vladimir Dmitrievich Plavskikh, ulitsa Kamenskaya,84v, kv. 33, all of Novosibirsk, USSR.

[22] Filed: Feb. 3, 1971 [21] Appl. No.: 112,350

[52] U.S. Cl 173/91, 91/234, 173/137 [51] Int. Cl E2lb 3/12 [58] Fieldof Search 173/91 [56] References Cited UNITED STATES PATENTS 3,137,4836/1964 Zinkiewicz 173/91 X FOREIGN PATENTS OR APPLlCATlONS 1,170,16711/1969 Great Britain 173/91 Primary Examiner-Ernest R. PurserAttorney-Waters, Roditi, Schwartz -& Nissen 57] ABSTRACT Pneumaticreversible percussion device used for making holes in the ground.

The device is characterized in that under the action of compressed airthe striker reciprocates in a hollow housing and delivers percussionsupon the latter, thereby making the device move in to the ground. Thecompressed air is supplied into working chambers of the housing along anair-supplying bushing having ports provided on its portion interactingwith the striker, overlapped by a slide valve during the forwardmovement of the device and used to outstrip the supply of compressed airinto a front chamber during the reverse movement of the device. Theslide valve is rigidly connected with a spring-loaded sleeve that isloosely mounted on the bushing and is actuated by a spring when thedevice is switched over to a reverse movement by way of dropping thepressure, as compared to the nominal one.

2 Claims, 2 Drawing Figures 1 REVERSIBLE PERCUSSION DEVICE The presentinvention relates to pneumatic reversible percussion devices for makingholes in the ground by way of compacting the latter, and can be used,for example, for constructing underground communications by theclosed'trench-less method.

Known in the prior art are pneumatic reversible percussion deviceshaving a housing pointed at its one side and accommodating a strikerforming two chambers, a front and a rear one, of a variable volume. Thefront chamber disposed between the housing and the outer surface of thestriker alternately communicates with a source of compressed air andwith the atmosphere. The rear chamber disposed inside the striker in thetail portion thereof constantly communicates with a source of compressedair.

An air-supplying bushing is fixed in the tail portion of the housing bymeans of a nut so that it can move in the axial direction with respectto the latter. From the rear chamber the compressed air is supplied intothe front one through ports made in the tail portion of the striker inthe course of interaction of the latter with the airsupplying bushing.

While reciprocating under the action of the com pressed air, the strikerimparts percussions to the housing, which displaces the latter in theground in the forward and reverse directions depending on the directionof the percussions.

To extract it from the well, the device is reversed by way of rotating ahose communicating with the airsupplying bushing and displacing thelatter relative to the nut, which results in a change in the rate ofsupply of the compressed air into the chambers and, consequently, in achange in the direction of the percussions delivered by the striker uponthe housing of the device.

The practice of use of such reversible percussion devices has shown,however, that there may take place a spontaneous stoppage of theair-supplying bushing in the nut during the forward movement of thedevice, which makes it difficult and sometimes impossible to reverse themovement of the device by way of rotating the hose.

The main object of the present invention is to provide a reversiblepercussion device whose movement would -be reversed by varying theworking pressure of the compressed air.

In accordance with the present invention this object is accomplished inthat the air-supplying bushing is rigidly fixed in the tail portion ofthe housing and its portion interacting with the striker is providedwith ports overlapped by a slide valve disposed inside the bushing andrigidly connected with a spring-loaded sleeve made movable along theair'supplying bushing.

It is expedient to connect the slide valve with the sleeve by means ofpins passed through the face wall of the bushing.

This constructive embodiment of the air-supplying bushing attributes toa more reliable operation of the device as a whole and simplifies itsservicing.

Other objects and advantages of the present invention will becomeapparent from the following detailed description of the invention, givenwith reference to the accompanying drawings, in which:

FIG. 1 shows a side view with a partial longitudinal section of areversible percussion device for making holes in ground, according tothe invention;

FIG. 2 is a section taken along line II-II in FIG. I.

The device comprises a hollow cylindrical housing 1 (FIG. 1) pointed inits front portion and accommodating striker 2 resting upon the innersurface of a bushing 7 with two belts 3 and 4.

The space confined by the inner surface of the housing 1 and the outersurface of the striker 2 forms a front working chamber 5 of a variablevolume, and the inner tail portion of the striker 2 has a space forminga rear working chamber 6. The chamber 6 accommodates the front portionof the air-supplying bushing 7 interacting with the striker 2,stationary fixed by a flange 8 in the tail portion of the housing 1 andconnected with a hose coming from a compressor.

The walls of the tail portion of the striker 2 are provided with ports 9which, depending on the position of the striker 2, periodicallycommunicate the from work ing chamber 5 either with the rear workingchamber 6 that is under constant pressure, or with the atmosphere.

The walls of the front portion of the air-supplying bushing 7,interacting with the striker 2, are provided with ports 10 used forsupplying compressed air into the front chamber 5 during the reversemovement of the device. Mounted inside the front portion of the bushing7 is a hollow slide valve 11 overlapping the ports 10 during the forwardmovement of the device.

Mounted on the bushing 7 at the side of the flange 8 is sleeve 12 (FIGS.1 and 2) having ports 13, made movable in the axial direction andrigidly connected with the slide valve 11 by means of pins 14 passedthrough the face wall of the bushing 7. Installed between the flange 8of the bushing 7 and the sleeve 12 is a spring 15 used to displace theslide valve 11 and the sleeve 12 during the reversing of the device.

The sizes and arrangements of the ports 9 and 10 are chosen so as toprovide for a constant value of their passage sections irrespective ofthe position of the striker.

The device functions as follows:

With the device operating under the conditions of the forward movement,the slide valve 11 and the sleeve 12, preferably connected to the formerby means of the pins 14, are moved under the action of the compressedair supplied into the rear working chamber 6 along the air-supplyingbushing 7 to the extreme position, as shown, whereby the ports 10 of thebushing 7 are overlapped by the slide valve ll, and the spring 15 iscompressed.

Concurrently, under the action of the compressed air supplied into thechamber 6, the striker 2 is moved to the left and delivers percussionsupon the inner wall of the front portion of the housing 1,. as a resultof which the whole device will move in the ground in the direction ofthe percussion, i.e., forward (in the drawing to the left). x

The friction forces arising between the housing 1 and the walls of thewell in the ground prevent the device from reverse displacement.

At the beginning of the forward stroke of the striker 2 the ports 9 inits tail portion connect the front working chamber 5 with atmosphere,and, as the striker 2 moves and interacts with the bushing 7 at apredetermined distance from the extreme front position thereof, theports 9 connect the front chamber 5 with the rear chamber 6, and,consequently, with the source of compressed air. Due to the jumping ofthe striker 2 from the front wall of the housing 1 and under the actionof the pressure of the compressed air delivered into the front chamber5, the striker 2 starts moving in the reverse direction (to the right)since its working area at the side of the chamber 5 is greater than thatat the side of the chamber 6.

With the ports 9 overlapped by the side surface of the air-supplyingbushing 7, the striker 2, by overcoming the resistance of the compressedair in the chamber 6, continues moving in the reverse direction due toexpansion of air in the chamber 5.

At the end of the reverse stroke of the striker 2 its ports 9, on havingpassed the stage of the great diameter of the bushing 7, connect thefront chamber 5, through the intermediary of the exhaust apertures 13 ofthe sleeve 12 and exhaust apertures 16 provided in the flange 8, withthe atmosphere, thus providing an outlet for the used air.

Then, the cycle is repeated. The forward movement of the device iseffected under the nominal pressure of the compressed air.

When the mechanism encounters an obstacle which it cannot overcome(boulders, remainders of a foundation, debris, etc.), or upon completionof the percussion drilling of a closed hole, there takes place reversingof the movement of the percussion device, as a result of which thelatter, after it has been supplied with compressed air, comes onto thesurface along the hole it has made before.

The reverse movement of the device takes place when the pressure of thecompressed air is lower than the nominal one. The rigidity of the spring15 is chosen in dependence on the value of the working pressure of theair of the reverse movement.

To make the device perform the reverse movement, the pressure of the airis to be dropped, whereby under the action of the spring 15 the sleeve12 and the slide valve 11 connected therewith will move to the extremeleft position shown in FIG. 1. As a result of this, the ports in thebushing 7 are opened, the sleeve 12 is pressed against the face wall ofthe bushing 7, and the exhaust ports 13 of the sleeve 12 are closed.

With the striker 2 displacing to the left, there takes placeoutstripping of the supply of the compressed air (as compared with thatduring the forward movement) into the front chamber 5 from theair-supplying bushing 7 through its ports 10 and the ports 9 provided inthe tail portion of the striker 2. The latter will be stopped by thecompressed air supplied into the chamber 5, and will start moving to theright without having delivered any percussion upon the front portion ofthe housing 1. Due to the increase in the volume of the front chamber 5and delay in the exhaust, as compared to the normal one, during itsreverse movement the striker 2 will deliver percussions upon the frontface of the forward flange of the bushing 7 rigidly secured in thehousing 1 of the device which in this case will move the device in thereverse direction along the hole it has made before.

To switch the device from the reverse movement over to the forward one,it is necessary to raise the pressure of the compressed air to thenominal one, whereby the pressure of the compressed air acting upon theslide valve 11 will exceed the force of the spring 15, and the slidevalve 11 with the sleeve 12 will move the extremeright position so thatthe slide valve 11 will overlap the ports 10.

Now, the supply of the air into the front chamber 5 will be controlledby the edges of the air-supplying bushing 7, and the striker 2 willdeliver percussions upon the front portion of the housing, e.i. theforward movement cycle of the device will take place again.

We claim:

1. A reversible percussion device for making holes in the ground bycompaction, comprising a housing pointed at one end and defining aninner space; a striker accommodated in said space and forming therewithfront and rear variable-volume working chambers which periodicallycommunicate with each other, said striker imparting impacts to saidhousing as it reciprocates therein under the effect of compressed airsupplied to said chambers; an air-supplying stepped bushing having apartition between the steps thereof and interacting by one of its endswith said striker, while the other end of said bushing is secured in aportion of said housing opposite to said pointed end, said one end ofthe bushing, which interacts with said striker, having ports therein forthe supply of the compressed air into said front chamber; a slide valvelocated inside said bushing for moving along the axis thereof to closesaid ports in one of its end positions; and a spring-biased sleeve formoving along said bushing and rigidly coupled with said slide valve.

2. The reversible percussion device as defined in claim 1, wherein saidslide valve is coupled with said sleeve by means of pins extendingthrough said partition between said steps of the bushing.

1. A reVersible percussion device for making holes in the ground bycompaction, comprising a housing pointed at one end and defining aninner space; a striker accommodated in said space and forming therewithfront and rear variable-volume working chambers which periodicallycommunicate with each other, said striker imparting impacts to saidhousing as it reciprocates therein under the effect of compressed airsupplied to said chambers; an air-supplying stepped bushing having apartition between the steps thereof and interacting by one of its endswith said striker, while the other end of said bushing is secured in aportion of said housing opposite to said pointed end, said one end ofthe bushing, which interacts with said striker, having ports therein forthe supply of the compressed air into said front chamber; a slide valvelocated inside said bushing for moving along the axis thereof to closesaid ports in one of its end positions; and a spring-biased sleeve formoving along said bushing and rigidly coupled with said slide valve. 2.The reversible percussion device as defined in claim 1, wherein saidslide valve is coupled with said sleeve by means of pins extendingthrough said partition between said steps of the bushing.